Thermal treatments affect the polyphenol profile and increase antioxidant capacity in five varieties of edible bean milks

We investigated the influence of two thermal treatments, steaming and boiling, on polyphenol profile and antioxidant capacity in milks from five edible bean varieties, including green mung bean milk, yellow and black soya bean milk, rice bean milk and white cow gram milk. The two thermal treatments had different influences on polyphenol profile and antioxidant capacity with steaming better than boiling in increasing total phenolic content (TPC) and antioxidant capacity in edible bean milks. In particular, steaming substantially increased soya bean isoflavone glucosides in the two soya bean milks. Bioconversion between polyphenols, the release of bound polyphenols and the induction of Maillard reaction products could contribute to the increase in TPC and antioxidant capacity in some edible bean milks. Therefore, it is recommended to steam edible bean milk for consumption, and edible bean milk containing antioxidant polyphenols can be developed into functional drinks with potential health benefits.

 genistin, daidzein and genistein were bought from Wako Pure Chemical Industries (Osaka, Japan),
and p-coumaric acid, ferulic acid, rutin and quercetin were purchased from Sigma-Aldrich, and
vitexin and isovitexin were purchased from Biopurify Phytochemicals (Chengdu ...


... Materials and Methods. Reagents. Casticin was purchased from Chengdu Biopurify
Phytochemicals Ltd. (Chengdu, China) and dissolved in dimethyl sulfoxide to prepare stock